1. Field of Invention
The present invention relates to a gas-powered tool and, more particularly, to a controller for controlling the supply of gas in such a gas-powered tool.
2. Related Prior Art
As disclosed in U.S. Pat. No. 5,799,648 issued on Sep. 1, 1998, a gas-powered tool 1 includes a handle 2, a barrel 6 extending from the handle 2, a head 4 connected to the barrel 6 and a tip 8 extending from the head 4. The handle 2 and the head 4 both are hollow. A reservoir 23 is located in the handle 2 for storing gas. A combustor 10 is located in the head 4 for burning the gas. A controller 28 is located in the barrel 6 for controlling the supply of the gas to the combustor 10 from the reservoir 23. A switch 32 is located between the reservoir 23 and the controller 28 for switching on/off the supply of the gas to the controller 28 from the reservoir 23. A throttle 29 is located in the barrel 6 for controlling the flow rate of the gas to the combustor 10 from the reservoir 23. The controller 28 includes a valve 39, a first element 70, a second element 71 and a permanent magnet 63 located between the first element 70 and the second element 71. The first element 70 is made of thermo-magnetic material. The second element 71 is made of magnetic material. The magnetic attraction between the permanent magnet 63 and the first element 70 is larger than the magnetic attraction between the permanent magnet 63 and the second element 71 when the first element 70 is magnetic. Thus, the valve 39 is open so that the gas goes into the combustor 10 from the reservoir 23 through the valve 39. The first element 70 becomes non-magnetic when the temperature reaches a limit. Therefore, the magnetic attraction between the permanent magnet 63 and the second element 71 is greater than the magnetic attraction between the permanent magnet 63 and the first element 70. Thus, the valve 39 is closed so that the gas goes into the combustor 10 from the reservoir 23 through the throttle 29. This conventional gas-powered tool 1 is, however, complicated in structure, difficult in fabrication and high in cost.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in the prior art.